Jack-screw



(No Model.)

0. H. HOPKINS.

. JACK SCREW.

Patented Feb. 26, 1889.

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CHARLES H. HOPKINS, OF LYNDONVILLE, ASSIGNOR TO SUMNER S. THOMP SON, OF LYNDON, VERMONT.

JACK-SCREW.

SPECIFICATION forming part of Letters Patent No. 398,617, dated February 26, 1889.

Application filed August l, 1888, Serial No. 281,704. (No model.)

To aZZ whom it may concern:

Be it known that 1', CHARLES H. HOPKINS, a citizen of the United States, residing at Lyndonville,in the countyoi' Caledonia and State of Vermont, have invented certain new and useful Improvements in Jack-Screws; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figijires of reference marked thereon, which form a part this specification.

My invention relates to an im1n'oven1ent in jack-screws; and it consists in the construction and arrangement oi the parts of the same, which will be more fully hereinafter described, and pointed out in the claims.

The object of my invention is to provide a jackscrew which is simple and eii'ective in its construction and operation, strong and durable, easily handled. and readily understood, 3

positive in its result, and cheaply manufaci I attain this object by the construction of a jack-screw, as illustrated in the actured.

companying drawings, wherein like letters of reference indicate similar parts in the several. Views, and in which- Figure l is a general view of my improved jack-screw. Fig. 2 is a vertical sectional view of the same. Fig. 3 is an elevation of the illner side of one of the lugs of the operatinghandle, showing the spring-actuated double acting pawl and ratchet used in connection therewith.

A indicates a suitable standard, which is constructed hollow and fits into the hollow cap B, forming the top piece of a hollow baserest, (1, and held in place by suitable screws, p q, or otherwise rigidly attached thereto. In the interior of standard A and separated therefrom by a bouching, G, is a second hollow cylinder, E, upon the upper end of which and rigidly attached thereto is a heavy cap,D, the upper surface of which is suitably scored. The inner lower portion of this cylinder E is constructed in the form of a nut, through which passes the screw F, which rests in a suitable socket in the bottom of the baserest C and having rigidly attached to it near the lower end one or more bevel-gears, K, of suitable size, which may be below or above the bevclgears ll and ll, into which they mesh, the gears II and L being rigidly at tached to stub-shafts I M, respectively. If greater power is required, a worm-gear may take the place oi the bevel-gear K, and a worm used instead of bevel-gears ll and L and stubshafts l M. The stulrshat'tsl' and M work in bonchings J and N, the side through which J projects being thickened for its snp lort, while the opposite side of the base-rest t, through which bouching N projects, has a boss, 1, formed on its outside for the same purpose.

1 Upon the stubshaftl or M (its an operatinghandle, 0, the innerlng of which plays freely upon the above-mentioned benching, which projects through the base-rest for that purpose, while the outer lug plays freely upon the stubshaft itself. Between the two lugs and to berigidly held in place by a suitable pin, 5, is a ratchet-wheel, 6. Over this and playing freely upon a pin, 12., passing through the lugs is a double pawl, g, from the top of which projects a stiff flat steel spring, f. From the inner lug of the handle projects a smaller spring, 1, the outer end of which presses into a slight recess in the shoulder of the pawl and serves to hold the latter in a middle position when the bar a is removed. Into aslot extending vertically through the upper portion of the operating-1m ndle Z) is placed a fiat iron lever-bar, at, having its lower end beveled. At a proper distance from the lower end of the bar a a pin, m, is put through it, or an enlargement in the handle may be made at that place, to prevent the bar going too far into the slot. The beveled edge on the lower end of the bar a acts to press the sprin over to one side and thus to force the toe of the double pawl on that side into engagement with the ratchet-wheel e as the handle is worked backward and forward. A reversal of the bar, so that the bevel will act in the opposite direction on the spring, will cause the other toe of the pawl to work in a similar manner.

In the standard A is an oil-hole, z", for lubrieating the screw F, and in the base-rest C is a similar hole, 72, for lubricating the socket in which screw F rests.

The operation of my improved jack-screw will be as follows: The bar a.,.being placed in the operating-handle 17, causes one toe of the double pawl g to engage with the ratchet-wheel e, and upon the handle being worked backward and forward the s'tub-shaftI or M is made to revolve, and consequently the bevel-gear H or L, which in turn causes the revolution of the bevel-gear K, and hence that of the screw E, which causes the cylindrical nut E to be raised or lowered according to the direction in which the bevclgears are made to revolve, as will be readily understood. By this means the main operating mechanism of the jackscrew is allowed to remain stationary as regards elevation while the cylindrical nut is gradually raised or lowered. The nut is prevented from turnin by the weight superimposed upon the cap D. \Vhen desired, the jack may be raised or lowered by hand by revolving the cap D in the direction desired. In this case the gears ll, L, and K would be held from working by the pawl engaging the ratchet-gear, as described. *hen desired, the nut may be raised or lowered without the use of the operating-handle by removing the bar 0 and centrally locating the pawl g, with the aid of the small spring 1', and then turning said cylindrical. nut E in either direction with the hands. ,7

By means of my form of construction of lifting jaekscrews a great power is brought to bear uponthe cylindrical nut E with but a small force, and by means of the double action of the pawl heretofore described the motion of the screw 1* and consequently of the nut may be readily reversed.

It will be noticed that the gears H and L are of different sizes, the object thereof being to obtain different powers. The larger gear is used when less power and quicker work are desired, and vice versa.

The novelty and utility of myimproved device being apparent, it need not further be en'- larged upon herein.

It is obvious that many minor changes in the casting, construction, and arrangement of the various parts may be made and substituted for those herein shown and described without departing in the least from the nature and principle of my invention.

I am aware that previous to my invention it has been proposed to construct a jack-screw wherein a dog was to be employed for engaging the pinion to effect its rotation in either direction. I am also aware that it is not new to employ a double-acting pawl controlled by a spring. My invention will be readily distinguished from the foregoing, in that the pawl-controlling spring is connected to said pawl and is forced into a position to do work by the beveled edge on the lower end of the bar a. An inuportant feature consists in the fact that by a simple reversal of the bar the power made to work in the opposite direction.

Having thus described my claim In a jack-screw, the combination, with-the standard, cap, and base-rest AB C, of a cylindrical nut, E, working on a screw, F, therein, the bevel-gear K, rigidly attached thereto, the bevel-gears H and L on the stub-shafts I and M at right angles to said gear K and engaginvention, 1

, ing therewith, a ratchet-wheel, e, that maybe Witnesses:

L. B. HARRIS, I. S. PEARL. 

